Fix warnings about deleting pointers to incomplete classes
Add accessor methods for stack values
Remove unused code.

Object definitions are handled earlier in the path, so this is dead code.
Copy the stack values in the copy constructor of HSSObject
Separate HSSObjectDefinition's apply into two phases: stack and computed

Managing the stack and the computed values are separate stages, they shouldn't
be conflated in one single apply method
Fix bug in tokenizer when reading dots

It was skipping the first char of the next token
Add initial support for Dot Notation
Trim whitespace